Zotero

Zotero is a free, open source citation management software. Citation management software—which includes other tools like EndNote and Mendeley—allows you to: 

• Conveniently and securely store, organize, and track sources based on project, class, theme, etc.
• Quickly generate citations and bibliographies in any style.
• Easily find sources you’ve previously saved.
• Practice active (and collaborative!) reading by digitally highlighting and commenting on PDFs.